Method of treating materials



UNITED STATES ATENT OFFlE PAUL P. ZIMMT ERMAN, OF CHICAGO, ILLINOIS, ASSIGNOR TO WESTERN ELECTRIC COM- PANY, INCORPORATED, OF NEW YORK,

N. Y., A CORPORATION OF NEW YORK METHOD OF TREATING MATERIALS No Drawing.

This invention relates to a method of treating materials, and more particularly to a method of heat treating powdered nickel-iron alloys.

Heretofore, in the manufacture of magnetic cores from finely divided magnetic material for use in telephone systems it has been practiced, after the alloy consisting of nickel and iron in desired proportions has been embrittl-ed and ground to a. dust of a finess that will pass through at least a 120 mesh screen, to anneal the dust at a high temperature. The purposes of annealing the dust is to impart to it the desired magnetic and electrlcal properties in order to make it particularly suitable for use in the manufacture of loading coils. Annealing the dust at the temperatures required to impart to it the desired magnetic properties has in some cases resulted in sintering of the powdered alloy,'requiring that additional operations be performed in order to produce the dust of the desired fineness.

Objects of the invention are to provide a method of improving the electrical, mag

netic, and physical properties of the alloy and facilitating and expediting the manufacture of the cor-e parts.

In a general embodiment of the invention the nickel-iron alloy is reduced to a powder, treated with a heavy oil, and thereafter heat treated at a temperature depending upon the constituents of the alloy to impart to the alloy particles the desired properties. The use of a heavy oil eliminates the sintering of the powdered alloy during the high temperature anneal, and thus eliminates the necessity of regrinding the material to reduce it to a powder after the high temperature anneal, which results in a reduction of the hysteresis loss of the powdered alloy, as well as an improvement in its other properties.

In accordance with one of the species of the present invention, 240 pounds of nickeliron dust or powder containing 81% nickel and 19% iron, is placed in a drum where 2.16 pounds of heavy oil such as resin oil, meprolene or any oil with an asphalt base, is mixed therewith. This quantity of oil which is mixed with the nickel-iron alloy Serial No. 477,194.

amounts to .90% of the amount of alloy. In order to facilitate the mixing of the oil with the powdered material, the oil and the material is heated to a low temperature of approximately 100 F thus making the oil less viscous. The material is then placed in an annealing box which is sealed and the box with the material is heated to a temperature of approximately 1625 F. for a period of approximately one and one-half hours, during which time the powdered particles of the material become annealed, yet they are separated from each other by the residue of the oil, thus eliminating sintering. By stating that sintering is eliminated, it is meant that the particles of material have not formed into a common metallic mass as occurs when the powdered material is annealed without previously being mixed with the oil. As the result of this process, the hysteresis loss at 20 gausses is reduced from 2.70 watts/cycle/cm to 1.95 watts/cycle/cm this being due to the elimination of the sintering and the necessity of regrinding the material into powdered form which, of course, would set up strains and stresses in the material. Therefore, by eliminating sintering the necessity of additional operations; namely, grinding and sifting, is avoided, and by avoiding these additional operations which impair the material magnetically, the hysteresis loss is reduced.

According to another of the species of the present invention, .12 of apound of heavy oil is mixed with 240 pounds of powdered nickel-iron alloy containing 81% nickel and 19% iron While heated at a low temperature of approximately 100 F. This amount of oil gives a mixture of 05% of oil to a quantity of powdered material. This mixture of material is then heated in a sealed annealing box at a temperature of approxi-' mately 1400 F. for a period of approximately one and one-half hours. As the result of this test, due to the elimination of sintering and the necessity of regrinding the material which set up strains and stresses in the material, the hysteresis loss at 20 gausses i reduced from 2.73 watts/cycle/cm to 2.29 watts/cycle/cm In accordance with another of the species of this invention .12 of a pound of heavy oil is mixed with 240 pounds of nickel-iron alloy containing 81% nickel and 19% iron, while heated at a low temperature of approximately 100 F. This quantity of oil amounts to 05% of oil to a quantity of powdered material. This mixed material is then heated to a temperature of approximately 1300 F. for a period of one and onehalf hours, and as a result of this test, due to the elimination of sintering, and the necessity of regrinding the materials to reduce it to powdered form which would set up strain and stresses in the material, the hysteresis loss at 20 gausses is reduced from 2.60 watts/cycle/cm to 2.39 watts/cycle/cm The annealing temperatures of powdered magnetic materials range from approxi mately 1300 F. to approximately 1980 F. and the quantity of oil mixed with the powdered material will vary according to the annealing temperature from approximately 05% of oil for a temperature of 1300 F. to approximately 1% of oil for a temperature of 1980 F. The greater the percentage of oil mixed with the powdered material, the greater will be the percentage of the residue of the oil remaining with the material after it is annealed and molded into cores, thus tending to weaken the molded material according to the quantity of oil used. However, this percentage of oil which is mixed with the powdered material is so small, that the reduction in the breaking strength of the molded material is not detrimental. By mixing a heavy oil with the powdered material, each particle is completely covered with the oil and separated from the other particles of the material. Furthermore, this covering of the particles of the material with oil eliminates sintering and a decrease of hysteresis loss results.

Although one certain type of oil has been mentioned as mixed with the permalloy powder and heated to certain annealing temperatures, it is obvious that other types of oil might be used at different temperatures without departing from the spirit and scope of the invention.

hat is claimed is:

l. A method of treating materials, which consists of mixing an oil with a powdered magnetic material, and annealing the material.

2. A method of treating materials, which consists of reducing a magnetic material to a powdered form, mixing an oil with the powdered material, and annealing the ma terial.

3. A method of treating materials to eliminate sintering, which consists of mixing an oil with a quantity of powdered magneticmaterial, and annealing the material.

4. A method of treating materials, which consists of mixing less than 1% of heavy oil with a powdered magnetic material, and annealing the material.

5. A method of treating materials, which consists of mixing 00% of oil with a quantity of powdered magnetic material, heating the mixture of powdered material and oil to a temperature of approximately 1625 F., and allowing the material to cool.

6. A. method of treating materials, which consists of mixing 05% of oil with a quantity of powdered magnetic material, and annealing the powdered material at a temperature of approximately 1 100 F.

7. A method of treating materials, which consists of mixing approximately 1% of oil with a quantity of powdered magnetic material, and heating the mixed material at a temperature of approximately 1980 F. for a period of approximately one and one-half hours.

8. A method of treating materials, which consists of mixing 05% of oil with a quantity of powdered magnetic material, and heating the mixed material at a temperature of approximately 1400 F. for a period of one and one-half hours.

9. A method of treating materials, which consists of mixing 05% of oil with a quantity of powdered magnetic material, and heating the mixed material at a temperature of approximately 1300 F. for a period of one and one'half hours.

10. A method of treating materials, which consists of mixing a quantity of oil with a quantity of powdered magnetic material, and heating the mixed material to an annealing temperature, the quantity of oil being variable according to the ten'iperature of anneal.

11. A method of treating materials to reduce the hysteresis loss thereof, consisting of mixing an oil with a powdered magnetic material. and annealing the material.

12. A method of treating materials to reduce the hysteresis loss thereof, consisting of mixing an oil with a powdered magnetic material to avoid sintering during annealing, and annealing the material.

In witness whereof, I hereunto subscribe my name this 16th day of August A. D., 1930. 1

PAUL P. ZIMMERMAN. 

